Sierra County Sheriff's Deputy Joe Mosley, 34, is one tough mountain cop, already legendary for the airtight heat he puts on drunken drivers and other high-country miscreants.

"Statistics-wise I'd have to say I'm up on top," the deputy acknowledged yesterday. Bigfoot is another legendary creature of the Northwest. Although confirmed statistics are entirely lacking on him, Bigfoot, or Sasquatch, is said to be one tough beast, hairy and ridiculously oversized.

Last Friday night three strangers knocked on the door of Deputy Mosley's residence in central Sierraville, barely a block away from the town's main saloons. It was not known how the strangers knew it was the deputy's house, but they carried word of frightening personal confrontations with Bigfoot. Mosley believed then they were sincere, and still does. "They were sober, and you could tell by their actions that they were honestly very scared of something," he said yesterday.

Sierra County in general is known for its sasquatch-sized practical jokes and tales. Mosley has been conned in the past into chasing nonexistent accidents by Sierraville-area saloon denizens who wish him out of town for a while, said sheriff's dispatcher Nora Prince, who added about the Bigfoot caper: "I think they set him up again."

But Mosley is sure it was not a trick this time. "They wouldn't have hung around and slept in their vehicle right in Sierraville, if it was a trick," he said confidently. "It takes a lot of nerve to tell someone you saw Bigfoot because you'll be called whacko."

The strangers told the deputy of stopping for a dusk coffee break at a Highway 89 rest area about 25 miles south of Sierraville, and only two miles north of Truckee, where there is a Nevada County sheriff's substation. "They heard a squealing noise, and then saw a 9- or 10-foot tall burnt-black animal standing on its hind legs about 100 to 150 yards away," Mosley said. "They said when it saw them, it took off in an easterly direction, walking fast on its hind legs, straight up like a man."

The deputy wrote up all this in a report, and yesterday the Bigfoot sighting recounted by Mosley on behalf of the three men, who haven't been seen since Saturday, was all over the region's airwaves and newspapers. Sierra County saloons were buzzing with speculation.

"Every little county has its No. 1 deputy that nobody likes. You know, the guy who parks in front of the bar at 2 a.m.," said Jim Shelton, bartender at the Golden West Tavern in Loyalton, 12 miles out of Sierraville. "If he's the guy they reported it to, they could well be pulling a trick on him."

Nah, Mosley said. "A ride-along civilian was with me, and he believed they were sincere. Maybe it was a bear or something, but they said they were loggers who had seen lots of bears in their work," he said. The middle-age strangers were driving an older pickup truck with Texas license plates. They gave names of Claude Dudley, Tommy Ruffing and Lee Janet III, and told Mosley they were itinerant loggers on their way to the J.B. Henderson Lumber Camp in Portland, Ore.

The two main umbrella organizations for logging and lumber companies in Oregon said yesterday that they had never heard of J.B. Henderson.